高深宽比微细结构电铸时传质过程数值分析  

Numericall Analysis on Mass Transport in Micro Electroforming of Micro Structures with High-aspect-ratio

作　　者：明平美[1] 朱荻[2] 胡洋洋[2] 曾永彬[2] 

机构地区：[1]河南理工大学机械与动力工程学院,焦作454000 [2]南京航空航天大学机电工程学院,南京210016

出　　处：《机械工程学报》2008年第8期195-201,共7页Journal of Mechanical Engineering

基　　金：江苏省自然科学基金(BK2004214)

摘　　要：针对高深宽比微细结构电铸时存在严重传质受限的问题,以微深槽特征为分析对象建立液相传质两种数学模型——维扩散模型和二维对流—扩散模型,并分别用Matlab专用工具箱和Fluent 6.2流体仿真软件进行数值求解,依次分析以扩散、强制对流-扩散、复合对流(强制对流和自然对流)-扩散等为主导传质模式作用下微细电铸时,流场和离子浓度场的空间变化规律及其对液相传质效果的影响,并进行试验验证。结果表明:微细结构电铸时,单一扩散作用仅能用于深宽比小于2且电流密度小于2A/dm^2的液相传质场合;槽外强制对流只能对深宽比小于2的微槽内电解液产生一定搅拌作用;强化槽内自然对流作用并与槽外强制对流协同配合时,槽(深宽比为5)内可形成独特的单个或多个占据整个槽空间的涡流循环胞,涡流流速约为强制对流流速的1/20～1/2,明显改善传质效果,试验结果与此相印证。Aiming at the problem of mass-transport limitation in the electroforming of microstmctures with high-aspect-ratio （HAR）, two kinds of numerical models of mass-transport （1-D diffusion model and 2-D diffusion-convection model） are developed. Distribution of flow field and ion-concentration field inside the micro-trench and their effect on mass transport efficiency governed by diffusion, forced convection-diffusion, and complex convection （forced convection and nature convection）-diffusion, respectively, are simulated and analyzed by using Matlab toolbox and Fluent 6.2 fluid simulation software, followed by some experiments to validate the numerical analysis results. The results indicate that diffusion-transport or forced convection transport outside the cavity does well only under the conditions of smaller HAR value （〈2） and lower current density （〈2 A/dm^2）; one or more vortex cells that occupy the whole cavity space can be formed in the cavity （aspect ratio = 5） when the natural convection inside the cavity is strengthened and collaborated with the forced convection outside the cavity. The vortex flow rate is about 1/20 - 1/2 of the forced convection flow rate, which results in a remarkably better transport efficiency; and experimental results agree well with numerical analysis results.

关 键 词：微细电铸 对流-扩散传质 高深宽比 微细结构 

分 类 号：TG662[金属学及工艺—金属切削加工及机床]